The sparse expanses of Northeast Colorado have become ground zero for a bizarre mystery surrounding sightings of nighttime coordinated flights of groups of drones. From roughly 7 pm to 10 pm every night last week, an estimated 17 drones with six-foot spans have flown "grid patterns" over Phillips County and near its border with neighboring Yuma County, according to Phillips County Sheriff Thomas Elliott. The drones operate at a few hundred feet in the air and were brightly lit with strobing colored and white lights, leaving local residents and those driving through the area baffled.